1. Field of the Invention
This invention pertains to a heat exchanger which uses rotating baffles with a spiral or concentric plate counter flow core to vary the inlet and outlet of the gasses in which heat is being exchanged in order to defrost efficiently the heat exchanger.
2. Description of the Prior Art
Control of frost formation has long been a source of energy consumption and equipment inefficiency in many electrically driven applications involving heating, cooling and ventilation. In these fields, one must deal with the accumulation of frost or ice on heat exchanger and air duct surfaces. Two common prior art approaches are the use of an automatic defrost cycle, where external energy is applied periodically to melt accumulated frost; and the use of a backup heat exchanger, which can be put into service while the primary heat exchanger is allowed to defrost naturally. These conventional approaches are deficient in that primary energy is often used to melt the frost directly; the equipment involved operates less efficiently as frost builds up prior to a periodic defrost cycle due to restricted air flow paths and reduced heat transfer effectiveness; and the latent heat of fusion of the frost is generally lost. Accordingly, much design effort is typically put into optimizing conventional periodic defrost cycles in terms of time and energy consumption.